I will second your recollection with my own memory of a recent historical find in the UK. IIRC, the Brit .gov has total say (not just first dibs) on historical artifacts. Basically “thanks for digging that up, old sod, we never would have found it without you — now begone with you...”
The Bits do pay finders for what they find but they do take the treasure after payment, probably don’t pay what the treasure is actually worth but 500,000 is better than nothing at all.